This section provides background information related to the present disclosure which is not necessarily prior art.
Disconnecting all-wheel drive vehicles are known in the art from various issued patents, such as U.S. Pat. No. 8,042,642 issued Oct. 25, 2011. Such disconnecting all-wheel drive vehicles employ a first disconnecting element in the front or primary driveline and a second disconnecting element in the rear or secondary driveline. It can be important in some instances that one or both of the first and second disconnecting elements exhibit a relatively low drag torque when not engaged (i.e., when not being used to actively transmit rotary power). It can also be important in some instances that one or both of the first and second disconnecting elements allow for rotational synchronization of the drive axle and the driveline before transmitting torque to the drive axles. Multi-plate wet clutches can serve as both a synchronizer and a torque transfer device. However, if one or both of the first and second disconnecting elements includes a multi-plate clutch pack, low drag is typically at least partially achieved by moving the clutch plates a sufficiently far distance from one another. In this regard, if the clutch plates are not separated by a sufficient distance, the disconnecting element can have a drag torque that can rival the drag torque of the (other) driveline components that are to be “disconnected”.
As the disconnecting drivelines must typically be capable of transmitting relatively high torque, the clutch packs employed in such devices generally include a relatively high number of clutch plates. Due to the need for a relatively high normal force to transmit high torque through such clutch packs, one common approach is to employ a hydraulically-powered actuator, which is fed hydraulic fluid via a high pressure pump, for applying the normal force. In order to sufficiently space or separate a large quantity of clutch plates, the actuator that applies the normal force to the clutch pack must have a relatively long travel. Due to the magnitude of the normal force and the relatively long length of travel, such friction clutches have a relatively long engagement time (i.e., a length of time between the point in time at which the friction clutch begins to engage and the point in time at which the friction clutch is fully engaged).
In view of the above remarks, an improved driveline component that is capable of being disconnected is needed in the art.